Dissolved Oxygen Analysis.pdf

Long Island Sound's water quality is impaired due to low dissolved oxygen levels, primarily caused by excessive nitrogen loading from various sources. The Total Maximum Daily Load (TMDL) analysis aims to reduce nitrogen loads to achieve water quality standards.

Key sources of nitrogen include:
- In-basin point sources (e.g., wastewater treatment plants)
- In-basin nonpoint sources (e.g., agricultural runoff, atmospheric deposition)
- Tributary import (e.g., rivers flowing into the Sound)
- Combined Sewer Overflows (CSOs) and stormwater loads
- Boundary loads (e.g., loads from outside the Sound's watershed)

The TMDL development process involves:
- Collecting ambient data and nutrient loading data
- Using a water quality model to project future conditions
- Developing nitrogen reduction plans

The TMDL allocation for nitrogen includes:
- In-basin sources: allocating loads to specific sources (e.g., wastewater treatment plants, nonpoint sources)
- Out-of-basin sources: allocating loads to sources outside the Sound's watershed
- Non-treatment alternatives: exploring alternatives to traditional wastewater treatment

Implementation of the TMDL will occur in phases, with ongoing public participation and reassessment. The goal is to reduce nitrogen loads and improve dissolved oxygen levels in Long Island Sound, ultimately achieving water quality standards.